Sheet metal is rolled up into coils at the end of its production. The ends of the material are normally somewhat ragged and must be squared. In addition it is standard to inspect the two faces of the workpiece to check their finish, and to gauge it also. Since the end of a rolled workpiece cannot be substantially different from, or at least no better than the rest of the workpiece, the cropping and inspecting operations are carried out at the same time.
Thus a machine is known which unwinds a short length of the end of the coil to allow both faces to be inspected, and which also crops off the ragged end, and even cuts off a piece for more intensive testing. Such a machine normally has a cradle on which the coil is supported and that is formed by a pair of horizontal rollers spaced apart by a distance slightly smaller than the minimum coil diameter likely to be be encountered. An opening element can engage tangentially against the coil which is rotated oppositely to the direction it is wound in so the workpiece end can be freed. A conveyor extends horizontally from this cradle to a pair of vertically spaced shear blades. As the coil is rotated in the cradle, the freed workpiece end is laid on the conveyor and forced between the blades so that it can be cropped.
In the known devices the upper and lower shear blades are carried on a frame that pivots about a horizontal axis. This frame also carries the opening element over which the workpiece strip is deflected before it passes through the narrow slot between the shear blades. The fairly stiff workpiece normally scrapes for several meters along the opening element and upper blade before flattening down on the conveyor, so that its surfaces are seriously marred, and it is very hard to grade.
In addition the lever assembly that actuates the shear is normally of complex and wear-prone construction. It must be serviced and repaired frequently, considerably adding to the operation costs of the apparatus.